From	Keith Briffa	Date	Mon Oct 13 16:36:52 2003
To	Kevin Trenberth, Michael E. Mann
CC	Caspar Ammann, ray bradley, Tom Crowley, Malcolm K. Hughes, Michael Oppenheimer, Tim Osborn, Jonathan T. Overpeck, Scott Rutherford, Tom Wigley, Phil Jones
Subject	Re: draft
Mike and all Hi , just back from a trip and only now catching up with important emails. Given the restricted time and space available to furnish a response to SB comments , I offer the following mix of comment and specific wording changes: I agree that the S+B response is designed to deflect criticism by confusing the issues rather than answering our points. In fact they fail to address any of the 3 specific issues we raised Namely , 1. the need for critical evaluation of proxy inputs , 2. the need for a consistent assimilation of widespread (dated and well resolved ) records, 3. the essential requirement for objective/quantitative calibration (scaling) of the input records to allow for assessment of the uncertainties when making comparisons of different reconstructions and when comparing early with recent temperatures. Their own , ill-conceived and largely subjective approach did not take account of the uncertainties and problems in the use of palaeodata that they chose to highlight in their opening remarks. I would be in favour of stating something to this effect at the outset of our response. Also , as regards the tree-ring bit , I fully concur with the sense of your text as regards Section 1, but suggest the following wording (to replace ",rarely for annual ring widths, and almost entirely at higher latitudes.") "but in certain high-latitude regions only. Where this is the case , these relatively recent (ie post 1950) data are not used in calibrating temperature reconstructions. In many other (even high-latitude) areas density or ring-width records display no bias." In the spirit of healthy debate - I agree with Tim's remarks , warning against presenting a too sanguine impression that the borehole debate is closed ( though I do think it is closing!). I also believe , as you already know, that the use of a recent padding algorithm to extend smoothed data to the present time, is inappropriate if it assumes the continuation of a recent trend. This is likely to confuse , rather than inform, the wider public about the current climate state . Finally , I repeat my earlier remarks (made before EOS piece published) that we are missing an opportunity to say that a warm Medieval period per se is not a refutation of anthropogenic warming , {as its absence is no proof}, if we do not understand the role of specific forcings (natural and anthropogenic) that influenced medieval and current climates. Cheers Keith At 12:48 PM 10/9/03 -0600, Kevin Trenberth wrote: Hi all Here are my suggested changes: toned down in several places. Tracking turned on Kevin Michael E. Mann wrote: Dear co-authors, Attached is a draft response, incorporating suggestions Kevin, Tom W, and Michael. I've aimed to be as brief as possible, but hard to go much lower than 750 words and still address all the key issues. 750 words, by the way, is our allotted limit. Looking forward to any comments. Feel free to send an edited version if you prefer, and I'll try to assimilate all of the suggested edits and suggestions into a single revised draft. If you can get comments to me within the next couple days, that would be very helpful as we're working on a late October deadline for the final version. Thanks for your continued help, mike ______________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: [1]mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [2]http://www.evsc.virginia.edu/faculty/people/mann.shtml -- **************** Kevin E. Trenberth e-mail: [3]trenbert@ucar.edu Climate Analysis Section, NCAR [4]www.cgd.ucar.edu/cas/ P. O. Box 3000, (303) 497 1318 Boulder, CO 80307 (303) 497 1333 (fax) Street address: 1850 Table Mesa Drive, Boulder, CO 80303 -- Professor Keith Briffa, Climatic Research Unit University of East Anglia Norwich, NR4 7TJ, U.K. Phone: +44-1603-593909 Fax: +44-1603-507784 [5]http://www.cru.uea.ac.uk/cru/people/briffa[6]/ References 1. mailto:mann@virginia.edu%A0 2. http://www.evsc.virginia.edu/faculty/people/mann.shtml 3. mailto:trenbert@ucar.edu 4. http://www.cgd.ucar.edu/cas/ 5. http://www.cru.uea.ac.uk/cru/people/briffa/ 6. http://www.cru.uea.ac.uk/cru/people/briffa/